1. Field of the Invention
The present invention relates to a laminated quarter-wave plate or a circularly polarizing plate adapted to compensation for birefringence, a liquid-crystal display device using the same and a method for producing the same.
2. Description of the Related Art
As a wave plate capable of providing a retardation of a quarter wavelength in a wide wavelength range of visible light, there is known a laminated quarter-wave plate in which a quarter-wave plate and a half-wave plate produced by uniaxial stretching are laminated on each other so that directions of in-plane slow axes of these plates intersect each other. For example, the laminated quarter-wave plate is widely used for the purpose of anti-reflection of a liquid-crystal display device (hereinafter referred to as “LCD”).
A TFT (Thin Film Transfer) drive type twisted nematic (TN) LCD is widely used in a notebook type personal computer, a monitor, etc. The TN-LCD has a disadvantage in that the viewing angle thereof is narrow. A VA- or IPS-LCD capable of providing a wide viewing angle have been developed and begun to be popularized for monitor use. The VA- or ISP-LCD, however, needs backlight electric power because the VA- or ISP-LCD is lower in luminance than the TN-LCD. Moreover, the VA- or ISP-LCD has been not applied to a notebook type personal computer requiring low electric power consumption.
On the other hand, it is known that frontal luminance of a multi-domain VA-LCD is improved when the laminated quarter-wave plate is disposed in one interlayer between a liquid-crystal cell and a polarizer while a laminated quarter-wave plate capable of providing circularly polarized light of reverse rotation is disposed in another interlayer. In this method, it is however difficult to obtain a wide viewing angle. This problem can be solved by the related art when a negative uniaxial phase retarder produced by biaxial stretching and a polarizer are laminated on each other. There is, however, a disadvantage in that the resulting film is made thick because a large number of plates must be laminated as well as production efficiency is made low because a large number of laminating steps is required.